1994 5.0 fuel pump circuit issue


Feb 24, 2016
So I have an intermittent fuel pump no-prime or shut down if I move my ECC from a horizontal to a vertical position.

So a few items:
- I know it’s solid state and orientation does matter
- I hear a relay clicking button can’t tell if it’s just the PDC relay and not the fuel relay
- in the inoperable position I have swapped relays to test for a bad one
- I can move the ECC while the car is running and the pump will shut down and then come back on

Based on the wiring diagram and in the inoperable position, I think that;
- I can jump the test connector (Wht/Pink to LGT B)
- if I get power to the pump then there is a short between the test connector splice to the
- if no ground to the pump then the short has to be somewhere between the splice and the pin connector (I think it is a this)

Just wanted to run this logic by people.
doesn’t seem that the ignition relay, the +12, or the DK Green monitor items would be of issue.

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Sounds like a broken wire, or a wire with corrosion.
Another possibility is that the connector to the PCM has terminals that do not have a tight fit with the connector, so that when you move the PCM the harness is pulling on the terminal either making a better or worse connection.
Thank so will check the 22 pin on the harness side connector. It does it with 2 different ECCs as I first though it was a bad ECC.

And I’d be right that if it’s a wire it’s the Lt Blue some where pin to PDC fuel relay?